Acoustic diaphragm



S. D. PADDACK.

ACOUSTIC DIAPHRAGM.

APPLICATION FILED Fis. 7*. 191s.

1,356,399.' l Patented oet 19,1920.

l INVENTOR @nidad/U ATTORNEY srA'res- 'PATENT oFFici-i.

siii/ion' ravin rnnnacx, or-BRooKLYN, NEW YonK,.Assrc-Non r.ro THE 130mm coMrANY, A conroaArIoN. oF CONNECTICUT.

ACUSTIG DIAPHKAGM.

Speccationof Letters Patent.

rae-)area oet. ia-ieac.

Application led. February 7, 191. Serial No. elastici..

To all 'whom it may concern.'

.Be it known that I, SiiiroNjDAvruPAD- BACK, citizen of the United States, residing at\ 28 Hawthorne street, Brooklyn,- State of New York, have invented new and useful Improvements in Acoustic Diaphragme, of which the following is a specification: t This invention pertains to acoustic diaphragms particularly for use in phonographs; and in sound-recording and reproducing instruments generally. f In the accompanying, drawing 1s .illustrated an acoustic diaphragm which is one of the embodiments that my broad invention is adapted to take. In said drawing, Fi are 1 is a face view of the diaphragm; and 1g.' 2 is a dia rammatical, enlarged vertical section on t e line 2-2 in Fig. 1, the middle portion being shown broken away. i

The preferred diaphragm comprises a suitable base such as blotting-paper having incorporated therewith shellac, resin, wax and finely divided glass.

To make it, I prefer to proceed as follows z-I melt together by the use of heat 40% by weight of shellac and 50% of resin. To this I add 10% of powdered glass and thoroughly -stir the ingredients. Then I add enough wax to make a considerable layer of it over the surface of the molten mixture, this waxy layer being renewed from,

time to time, if necessary, as it becomes used up during the next step of the process. This consists in slowly passing blotting-paper through the molten mixture preferably .in a long strip, wider lthan the finished. diaphragms. The forward vend vof the strip as it emerges from the bath then passes between heated pressure-rolls, which complete the impregnation of the blotting-paper with the shellac and resin and force the powdered glass into the paper.v At the same time the rolls remove the excess material .and compress the paper, making it ,denser and harder. As the strippasses through the waxy layer from the molten I nixture'to the rolls, it carries with it a considerable quantity of the wax which becomes incorporated withthe paper strip as it passes through the rolls, especially at the surface of the paper, the wax being preferably thelast ingredient to be applied.

,After a short'interval the individualv diaphragms can be cut from the strip by the use of cutting dies or the like. The resulting diaphragms used in phonograph souned- I boxes give excellent reproductions.

Changes can be made in the above process, the ingredients and their proportions which will still be within the spirit of the invention and by such suitable modifications diaphragms can be made which will neverthe' less be within claims.

The slellac and resin constitute broadly a binder besides making their own several contributions to the properties of the preferred my invention and the annexed diaphragme The glass contributes to the brilliancy and other desirable acoustic properties of the diaphragm. While glass is preferred, it is possible to employ other finely divided vitreous material such as silica, obsidian, etc., or in general any mineral which is insoluble in the binder and has sonorous qualities similar to glass. The diaphragm is not materially affected by dampness and to this quality the wax contributes. Instead of blotting-paper, any other suitable base may be used. but preferably it should be porousor absorbent. Depending on the precise acoustic quality desired fol1 the diaphragms, the above process can be made longer or shorter in duration so as to impregnate the base more or less completely from its surface layers -inwardly to its center layer or zone.

However, the diaphragm I prefer is the one which is not impregnated to the center zone. In this preferred diaphragm the resin and shellac penetrate from each surface of the disk about or so through the thickness of the disk, and the powdered glass ingredient penetrates from the surface about l the penetration lof the resin and shellac. This embodiment of my invention is illustrated diagrammatically in the drawing wherein in Fig. '2, A for example, designates the entire thicknessof the paper base, B the surface layers impregnated with the resin and. shellac, C the shallower surface layers containing embedded therein the powdered glass` suitable base having powdered glass combined therewith. l 2. An acoustic dia hragrnI comprising a suitable base having E material combined therewith. p

3. An acoustic diaphragm comprising powdered glass and a binder incorporated with a suitable base which is absorbent to the binder.

4. An acoustic diaphragm comprising a resonant moisture proof binder, a suitable absorbent base therefor, and powdered glass, the binder and glass being absorbed and pressed into the surface'of the base.

5. An acoustic diaphragm comprising a suitable base having shellac, powdered glass, andresinincorporated therewith.

6. An acoustic diaphragm comprising a suitable base having shellac, a finely divided mineral and resin incorporated therewith, the mineral having sonorous qualities similarto glass.

Y 7. An acoustic diaphragm comprising a l suitable base having shellac, powdered glass,

wax and resin incorporated therewith.

8. An acoustic diaphragm comprising a suitable base having shellac, a finely divided mineral, wax and resin incorporated therewith, the mineral having sonorous qualitiessimilar to glass.

9. An -acoustic diaphragm comprising a nely divided vitreous 11. An acoustic diaphragm comprising a A suitable base having incorporated therewith a binder of resonant material, a wax and a finely divided mineral insoluble in the binder.

12. An acoustic diaphragm comprising a suitable base having incorporated therewith shellac, resin and a finely divided mineral insoluble in the shellac and resin and having sonorous properties similar to glass.

13. An acoustic diaphragm comprising a suitable base whose surface layers only are filled with a finely divided vitreous material and whose surface layers are also impregvnated with a binder which extendsrthrough and below the vitreous material, leaving the central Zone of the base unimpregnated.

14. An acoustic diaphragm comprising a suitable base of fibrous material having finely divided, hard, sharp vitreous material embedded in its surface.

In testimony whereof I, said SIMON DAVID PADDAQK have signed my name to this specification this 5th day of February, 1918.

SIMON DAVID PADDAGK. 

